EP1279175B1 - Composition magnetorheologique - Google Patents

Composition magnetorheologique Download PDF

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Publication number
EP1279175B1
EP1279175B1 EP01932974A EP01932974A EP1279175B1 EP 1279175 B1 EP1279175 B1 EP 1279175B1 EP 01932974 A EP01932974 A EP 01932974A EP 01932974 A EP01932974 A EP 01932974A EP 1279175 B1 EP1279175 B1 EP 1279175B1
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Prior art keywords
magnetorheological
magnetic
particles
responsive particles
magnetorheological composition
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German (de)
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EP1279175A2 (fr
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Andrew K. Kintz
Teresa L. Forehand
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Lord Corp
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Lord Corp
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/44—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of magnetic liquids, e.g. ferrofluids
    • H01F1/447—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of magnetic liquids, e.g. ferrofluids characterised by magnetoviscosity, e.g. magnetorheological, magnetothixotropic, magnetodilatant liquids

Definitions

  • the invention relates to magnetorheological compositions that have improved performance when exposed to magnetic fields. More specifically, the present invention relates to large particle magnetorheological compositions which have improved controllability.
  • Magnetorheological fluids are magnetic field responsive fluids containing a field polarizable particle component and a liquid carrier component. Magnetorheological fluids are useful in devices or systems for controlling vibration and/or noise. Magnetorheological fluids have been proposed for controlling damping in various devices, such as dampers, shock absorbers, and elastomeric mounts. They have also been proposed for use in controlling pressure and/or torque in brakes, clutches, and valves. Magnetorheological fluids are considered superior to electrorheological fluids in many applications because they exhibit higher yield strengths and can create greater damping forces.
  • the particle component compositions typically include micron-sized magnetic-responsive particles.
  • the magnetic-responsive particles In the presence of a magnetic field, the magnetic-responsive particles become polarized and are thereby organized into chains of particles or particle fibrils.
  • the particle chains increase the apparent viscosity (flow resistance) of the fluid, resulting in the development of a solid mass having a yield stress that must be exceeded to induce onset of flow of the magnetorheological fluid.
  • the particles return to an unorganized state when the magnetic field is removed, which lowers the viscosity of the fluid.
  • the magnetic-responsive particles in the magnetorheological fluids are comprised of spherical ferromagnetic or paramagnetic particles typically 1 to 10 microns in diameter, dispersed within a carrier fluid.
  • Small magnetic particle size permits easy suspension and the design of devices having small gaps.
  • there are a number of disadvantages to using small size particles For example, there is an insufficient supply of fine magnetic-responsive particles for applications in which magnetorheological technology may apply.
  • the use of fine particle iron limits the range of metallurgy that can be used due to the process used to obtain such particles.
  • Carbonyl iron the most commonly used iron, is derived from iron pentacarbonyl salts.
  • the particles are "grown" by precipitation, resulting in a spherical unreduced particle with a very low carbon content.
  • blends of various metals could be made and then reduced in size by particle reduction methods.
  • small metal powders may be difficult to process since they can become dust explosion hazards when they approach a micron in size.
  • small diameter magnetic-responsive particles are much more expensive than larger particles.
  • US-A-5,354,488 discloses a magnetorheological fluid comprising a vehicle, magnetizable particles suspended in the vehicle and a dispersant.
  • the magnetizable particles are spherical.
  • the dispersants can consist of various solid materials.
  • This invention provides such a composition.
  • the present invention is directed to a magnetorheological composition
  • a magnetorheological composition comprising
  • the present invention is further directed to a magnetorheological device comprising the magnetorheological composition of the present invention.
  • the magnetorheological device has a specified design gap and employs compositions comprising magnetic-responsive particles having an average number diameter distribution (d50) of from 6 to 100 ⁇ m, preferably 10 to 60 ⁇ m and at least one additive that reduces the interparticle friction between the magnetic-responsive particles.
  • the additive is selected from an inorganic molybdenum compound, a fluorocarbon polymer or mixtures thereof.
  • the magnetic-responsive particles are 60 to 90 weight percent of the total magnetorheological composition.
  • the magnetic-responsive particles are irregular or non-spherical in shape.
  • the magnetorheological fluid comprises non-spherical magnetic-responsive particles having an average number diameter distribution d 50 of 6 to 100 ⁇ m, a carrier fluid and at least one additive that reduces the interparticle friction between the magnetic-responsive particles.
  • the magnetorheological fluid may comprise non-spherical magnetic-responsive particles produced by water atomization, at least one additive that reduces the interparticle friction between the magnetic-responsive particles, and a carrier fluid.
  • Form output means the damping force, torque, braking force or similar force depending on the device.
  • Yield strength is the force required to exceed the yield stress.
  • the “yield stress” is the stress that must be exceeded to induce onset of flow of the magnetorheological composition when subject to the presence of a magnetic field or in the "on-state.” The absence of a magnetic field is referred to herein as the “off-state.”
  • On-state forces as used herein are the resultant forces of a device as a result of applying a magnetic field.
  • Off-state forces means the forces generated by a device when no magnetic field is applied.
  • the present invention provides magnetorheological compositions which can be used in magnetorheological devices employing narrow design gaps and provide improved performance when exposed to magnetic fields.
  • the magnetorheological compositions provide improved on-state and off-state performance when exposed to magnetic fields.
  • the present invention provides magnetorheological compositions which deliver reduced on-state and off-state forces when used as or in a magnetorheological fluid. It has long been desirable to utilize large, non-spherical particles for magnetorheological fluid compositions due to the expensive nature of the spherical, small-size magnetic-responsive particles presently available for such use.
  • the present invention provides a magnetorheological device employing a composition comprising particular sized magnetic-responsive particles and an additive which reduces the interparticle friction between the particles.
  • a magnetorheological fluid controllable damper has essential components of a stationary housing, movable piston and field generator.
  • the housing contains a volume of magnetorheological (MR) fluid.
  • An MR damper has two principal modes of operation: sliding plate and flow (or valve) modes. Components of both modes will be present in every MR damper, with the force component of the flow or valve mode dominating.
  • the damper functions as a Coulomb or Bingham type damper, in which the force generated is desiredly independent of piston velocity and large forces can be generated with low or zero velocity. This independence improves the controllability of the damper making the force a function of the magnetic field strength, which is a function of current flow in the circuit.
  • Fig. 7 depicts in crossectional side view, a simple schematic of the piston portion of an MR device, well known in the art and more fully illustrated in U.S.-A-5,277,281, published Jan. 11, 1994 .
  • a piston is located within the housing (not shown).
  • Piston head 30 on piston rod 32 is formed with a smaller maximum diameter than the inner diameter of the housing.
  • the depicted piston embodiment contains coil 40 wound on core element 43 and residing in cup member 53.
  • piston rod 32 is connected to a first end of an electrically conductive rod which extends through piston rod 32, a lead connected to a first end of coil windings and a ground lead from the other end of the coil winding.
  • the upper end of piston rod 32 not shown has threads formed thereon to permit attachment to the damper.
  • An external power supply which provides a current in the range of 0-4 amps at a voltage of 12-24 volts, depending upon application, is connected to the leads.
  • Cup member 53 has a plurality of passageways 56 each having a predefined gap formed therein. In other typical embodiments, the gap is provided in an annulus. One or more seals such as at 54 extend about the periphery of cup member 53. Cup member 53 is attached to core element 43 by any fastening means, such as by threaded fasteners, not shown. A coil may alternatively be associated with the housing providing the possibility of a more stationary coil if desired.
  • the device of the present invention utilizes a predefined annular flow gap ranging from 0.1 to 0.75 mm, and preferably 0.4 to 0.6 mm. The gap is desiredly small so as to provide compact MR fluid devices that generate a relatively high on-state force.
  • Particle components such as carbonyl iron are readily usable in MR devices with these gap sizes and do not produce stiction.
  • Irregular-shaped particles of a larger average particle diameter (d 50 ) however exhibit stiction in devices with gap sizes of from 0.08 mm to 0.75 mm, especially 0.08 to 0.4 mm. Stiction, is evidenced by force spikes or irregular output forces of the piston, and is a particular problem at low piston speeds.
  • the magnetic-responsive particles employed in the present invention may be any solid known to exhibit magnetorheological activity.
  • Typical particle components useful in the present invention are comprised of, for example, paramagnetic, superparamagnetic or ferromagnetic compounds.
  • Specific examples of magnetic-responsive particles which may be used include particles comprised of materials such as iron, iron alloys, iron oxide, iron nitride, iron carbide, carbonyl iron, chromium dioxide, low carbon steel, silicon steel, nickel, cobalt, and mixtures thereof.
  • the iron oxide includes all known pure iron oxides, such as Fe 2 O 3 and Fe 3 O 4 , as well as those containing small amounts of other elements, such as manganese, zinc or barium. Specific examples of iron oxide include ferrites and magnetites.
  • the magnetic-responsive particle component can be comprised of any of the known alloys of iron, such as those containing aluminum, silicon, cobalt, nickel, vanadium, molybdenum, chromium, tungsten, manganese and/or copper.
  • Iron alloys which may be used as the magnetic-responsive particles in the present invention include iron-cobalt and iron-nickel alloys.
  • the iron-cobalt alloys preferred for use in the magnetorheological compositions have an iron:cobalt ratio ranging from 30:70 to 95:5, and preferably from 50:50 to 85:15, while the iron-nickel alloys have an iron-nickel ratio ranging from 90:10 to 99:1, and preferably from 94:6 to 97:3.
  • the iron alloys may contain a small amount of other elements, such as vanadium, chromium, etc., in order to improve the ductility and mechanical properties of the alloys. These other elements are typically present in an amount that is less than 3.0% by weight.
  • the most preferred magnetic-responsive particles for use in the present invention are particles with a high iron content, generally greater than or at least 95% iron.
  • the magnetic-responsive particles used will have less than 1%, more preferably less than 0.05% by weight carbon.
  • the magnetic-responsive particles will contain 98% to 99% iron, and less than 1% oxygen and nitrogen.
  • Such particles may be obtained, for example, by water atomization or gas atomization of molten iron. Iron particles with these characteristics are commercially available.
  • Examples of magnetic-responsive particles useful in the present invention include Hoeaganes® FPI, 1001 HP and ATW230. Other preferred particles include stainless steel powders such as 430L and 410L.
  • the particle component according to the invention is typically in the form of a metal powder.
  • the particle size of the magnetic-responsive particles should be selected so that it exhibits multi-domain characteristics when subjected to a magnetic field.
  • Average number particle diameter distribution for the magnetic-responsive particles are generally between 6 and 100 ⁇ m, preferably between 10 and 60 ⁇ m. In the most preferred embodiment, the average number particle diameter distribution of the magnetic-responsive powder is 15 to 30 ⁇ m.
  • the particle component may contain magnetic-responsive particles of a variety of sizes, so long as the average number particle diameter distribution is as set forth.
  • the particle component will have at least 60% particles which are at least 16 ⁇ m in diameter. Most preferably, the particle component will have at least 70% particles which are at least 10 ⁇ m in diameter.
  • the size of the magnetic-responsive particles may be determined by scanning electron microscopy, a laser light scattering technique or measured using various sieves, providing a particular mesh size.
  • the magnetic-responsive particles of the present invention may be spherical in shape, but will preferably have an irregular or non-spherical shape.
  • a particle distribution of non-spherical magnetic-responsive particles according to the present invention may have some nearly spherical particles within the distribution. However, more than 50-70% of the particles in the preferred embodiment will have an irregular shape.
  • Figure 5 is a scanning electron micrograph of spherical carbonyl iron particles derived from pentacarbonyl salts.
  • Figure 6 is a scanning electron micrograph of non-spherical iron particles which were obtained by water atomization. The content of the iron particles is about the same for both Figures 5 and 6 , having 99% iron, less than 1% nitrogen and 1% oxygen and less than 0.05% carbon.
  • the most preferred magnetic-responsive particles useful in the present invention are iron particles containing at least 99% iron and of the size and shape obtained by water atomization.
  • the magnetic-responsive particles are present in the magnetorheological composition in an amount of 60 to 90% by weight of the total magnetorheological composition, preferably in an amount of 65 to 80% by weight.
  • the magnetorheological compositions of the invention include one or more additives which reduce the interparticle friction between the magnetic-responsive particles.
  • the magnetorheological compositions thus obtained provide improved performance when used in a magnetorheological fluid composition.
  • magnetorheological fluids composed of a carrier fluid such as oil and irregularly shaped, large iron particles were found to have high on- and off-state forces when used in a device such as a damper. These fluids also produce sporadic peaks in the performance curves that occur mainly upon change of direction in the damper.
  • use of additives with irregularly-shaped particles would reduce off-state forces and increase on-state forces.
  • the additives according to the invention were found to lower on-and off-state forces and improve the performance of magnetorheological fluids compared to magnetorheological fluids containing non-spherical magnetic-responsive particles without an additive which reduces interparticle friction. Although it is less desirable to reduce on-state forces, such reduction was minimal in view of the advantages in the reduction of off-state forces. In particular, the reduction of off-state forces ranged from 2% to 20%, and the on-state forces were reduced by 3% to 20%. While not wishing to be bound by any theory, it is believed that the additives work to coat the metallic particles or to intermingle between the magnetic-responsive particles to serve as a friction-reducing medium. It further is believed that these additives may also interact with the surface of the device to provide a reduction in friction generated between the fluid and the device.
  • the additives of the present invention useful for the reduction of interparticle friction include inorganic molybdenum compounds or fluorocarbon polymers. Additionally, combinations of inorganic molybdenum compounds may be used, as well as mixtures of fluorocarbon polymers. A combination of any of these compounds, where appropriate, may also be used as the additive in the present invention.
  • the inorganic molybdenum compounds will be molybdenum sulfides or molybdenum phosphates. In the most preferred embodiment, the additive is molybdenum disulfide.
  • the preferred fluorocarbon polymers are tetrafluoroethylene, a fluorinated ethylene-propylene polymer or a hexafluoropropylene epoxide polymer.
  • the additive is polytetrafluoroethylene.
  • the friction-reducing additive may be present in an amount of 0.1 to 10 weight percent based on the total weight of the magnetic-responsive particles. In a preferred embodiment, the friction-reducing additive component is present in an amount of 1 weight percent to 50 weight percent, and more preferably from 2 to 4 weight percent, based on the total weight of the magnetic-responsive particles.
  • the magnetic-responsive particles and the friction-reducing additive may be provided, where appropriate, as a substantially dry powder mixture.
  • substantially dry means that the powders generally will have less than 1 % water or moisture. In a preferred embodiment, the powders will have less than 0.5 % moisture.
  • the dry powder mixture can be used in the dry form for appropriate applications.
  • a carrier fluid may be added to the powder mixture of magnetic-responsive particles and friction-reducing additive to provide a magnetorheological fluid.
  • the magnetorheological compositions of the invention may be provided as a dry premixture, absent a carrier fluid, or combined initially with a carrier fluid as is convnetional to provide a magnetorheological fluid composition.
  • the amount of magnetorheological composition in the magnetorheological fluid depends upon the desired magnetic activity and viscosity of the fluid. Generally, the amount of magnetorheological composition in the magnetorheological fluid will be from 5 to 50, preferably from 10 to 30 percent by volume based on the total volume of the magnetorheological fluid.
  • the carrier component is a fluid that forms the continuous phase of the magnetorheological fluid.
  • the carrier fluid used to form a magnetorheological fluid from the magnetorheological compositions of the invention may be any of the vehicles or carrier fluids known for use with magnetorheological fluids. If the magnetorheological fluid is to be an aqueous fluid, one of skill in the art will understand which of the additives disclosed herein are suitable for such systems. Aqueous systems are described, for example, in U.S.-A-5,670,077 . Where a water-based system is used, the magnetorheological fluid formed may optionally contain one or more of an appropriate thixotropic agent, an anti-freeze component or a rust-inhibiting agent, among others.
  • the carrier fluid will be an organic fluid, or an oilbased fluid.
  • suitable carrier fluids which may be used include natural fatty oils, mineral oils, polyphenylethers, dibasic acid esters, neopentylpolyol esters, phosphate esters, synthetic cycloparaffins and synthetic paraffins, unsaturated hydrocarbon oils, monobasic acid esters, glycol esters and ethers, silicate esters, silicone oils, silicone copolymers, synthetic hydrocarbons, perfluorinated polyethers and esters and halogenated hydrocarbons, and mixtures or blends thereof.
  • Hydrocarbons such as mineral oils, paraffins, cycloparaffins (also known as naphthenic oils) and synthetic hydrocarbons are the preferred classes of carrier fluids.
  • the synthetic hydrocarbon oils include those oils derived from oligomerization of olefins such as polybutenes and oils derived from high alpha olefins of from 8 to 20 carbon atoms by acid catalyzed dimerization and by oligomerization using trialuminum alkyls as catalysts. Such poly- ⁇ -olefin oils are particularly preferred carrier fluids.
  • Carrier fluids appropriate to the present invention may be prepared by methods well known in the art and many are commercially available, such as Durasyn® PAO and Chevron Synfluid PAO.
  • the carrier fluid of the present invention is typically utilized in an amount ranging from 50 to 95, preferably from 70 to 90, percent by volume of the total magnetorheological fluid.
  • the magnetorheological fluid may optionally include other components such as a thixotropic agent, a carboxylate soap, an antioxidant, a lubricant and a viscosity modifier, among others.
  • a thixotropic agent such as lithium stearate, lithium hydroxy stearate, calcium stearate, aluminum stearate, ferrous oleate, ferrous naphthenate, zinc stearate, sodium stearate, strontium stearate and mixtures thereof.
  • carboxylate soaps include lithium stearate, lithium hydroxy stearate, calcium stearate, aluminum stearate, ferrous oleate, ferrous naphthenate, zinc stearate, sodium stearate, strontium stearate and mixtures thereof.
  • antioxidants include zinc dithiophosphates, hindered phenols, aromatic amines, and sulfurized phenols.
  • lubricants include organic fatty acids and amides, lard oil, and high molecular weight organic phosphorus and phosphoric acid esters and examples of viscosity modifiers include polymers and copolymers of olefins, methacrylates, dienes or alkylated styrenes.
  • the amount of these optional components typically ranges from 0.25 to 10 volume percent, based on the total volume of the magnetorheological fluid.
  • the optional ingredient or ingredients will be present in the range of 0.5 to 7.5 volume percent based on the total volume of the magnetorheological fluid.
  • the optional thixotropic agent is any agent which provides thixotropic rheology.
  • the thixotropic agent is selected based on the desired carrier fluid. If the magnetorheological fluid is formed with a carrier fluid which is an organic fluid, a thixotropic agent compatible with such a system may be selected. Thixotropic agents useful for such organic fluid systems are described in U.S. - A - 5,645,752 . Preferably, oil-soluble, metal soaps, such as the carboxylate soaps listed above are used.
  • the viscosity of the magnetorheological fluid containing the magnetorheological compositions of the present invention is dependent upon the specific use of the magnetorheological fluid. One of skill in the art will determine the necessary viscosity according to the desired application for the magnetorheological fluid.
  • the magnetorheological fluids made from the magnetorheological compositions of the present invention may be used in a number of devices, including brakes, pistons, clutches, dampers, exercise equipment, controllable composite structures and structural elements. Magnetorheological fluids formed with the magnetorheological compositions of the present invention are particularly suitable for use in devices that require exceptional durability such as dampers.
  • damper means an apparatus for damping motion between two relatively movable members. Dampers include, but are not limited to, shock absorbers such as automotive shock absorbers.
  • magnetorheological dampers described in U.S.-A-5,277,281 and 5,284,330 are illustrative of magnetorheological dampers that could use the magnetorheological fluids obtained by use of the magnetorheological compositions of the present invention.
  • the magnetic-responsive particles of the present invention may be obtained in a number of ways.
  • the metal powder to be used as the magnetic-responsive particles of the invention is obtained by a water atomization process. This method contributes to reduce the total cost of a magnetorheological composition according to the present invention.
  • Water atomization is described in Powder Metallurgy Science by Randall M. German, 2nd Ed., Chap. 3, "Powder Fabrication,” pp.107-110 ( ⁇ 1984, 1999 ), as the most common technique for producing elemental and alloy powders from metals which melt below approximately 1600°C. This method involves directing high pressure water jets against the melt stream, forcing disintegration and rapid solidification. Because of rapid cooling, the powder shape is irregular and rough.
  • Figure 6 illustrates an example of the particle size and shape obtainable by water atomization.
  • the magnetic-responsive particles of the invention may be obtained by any method known in the art for the preparation of such particles. These methods include the reduction of metal oxides, grinding or attrition, electrolytic deposition, metal carbonyl decomposition, rapid solidification, or smelt processing.
  • Various metal powders that are commercially available include straight iron powders, reduced iron powders, insulated reduced iron powders, cobalt powders, and various alloy powders such as [48%]Fe/[50%]Co/[-2%]V powder available from UltraFine Powder Technologies.
  • a magnetorheological fluid was prepared by mixing 20% ATW-230 iron (a water-atomized, irregular shaped large particle powder containing 99% iron, less than 1% oxygen, less than 1% nitrogen and 0.01% carbon), 1% lithium hydroxy stearate, 1% molybdenum disulfide and the remaining volume (78%) of a synthetic hydrocarbon oil derived from poly- ⁇ -olefin sold under the name Durasyn® 162.
  • ATW-230 iron a water-atomized, irregular shaped large particle powder containing 99% iron, less than 1% oxygen, less than 1% nitrogen and 0.01% carbon
  • 1% lithium hydroxy stearate 1%
  • molybdenum disulfide derived from poly- ⁇ -olefin sold under the name Durasyn® 162.
  • the fluid obtained was tested in a truck seat damper and the results illustrated in Figure 1a , which shows the performance curve of force (1b.) vs. velocity (in sec.), and Figure 1b , which shows the performance
  • the test procedure measured the forces produced in the seat damper with a 2.54 cm (one inch) stroke at 5.08 and 20.32 cm/s (2 and 8 in/s) and 0, 1 and 2 amps.
  • the force spikes evident in the comparative example ( Figures 4a and 4b ) have been significantly reduced after the addition of 1% molybdenum disulfide to the magnetorheological fluid formulation, as shown in Figures 1a and 1b .
  • the off-state forces were decreased from 72.48 kg to 58.89 kg (160 lbs to 130 lbs) and the on-state forces were decreased from 267.27 kg to 217.44 kg (590 lbs to 480 lbs).
  • a magnetorheological fluid was prepared by mixing 20% ATW-230 iron, 1% lithium hydroxy stearate, 2% molybdenum disulfide and the remaining volume (77%) of a synthetic hydrocarbon oil derived from poly- ⁇ -olefin sold under the name Durasyn® 162.
  • the fluid obtained was tested in a truck seat damper and the results illustrated in Figure 2a , which shows the performance curve of force vs. velocity, and Figure 2b , which shows the performance curve of force v. relative position.
  • the test procedure measured the forces produced in the seat damper with a 2.54 cm (one inch) stroke at 5.08 and 20.32 cm/s (2 and 8 in/s) and 0, 1 and 2 amps.
  • a magnetorheological fluid was prepared by mixing 20% ATW-230 iron, 1% lithium hydroxy stearate, 4g (8 %) teflon and the remaining volume (71 %) of a synthetic hydrocarbon oil derived from poly- ⁇ -olefin sold under the name Durasyn® 162.
  • the fluid obtained was tested in a truck seat damper and the results illustrated in Figure 3a , which shows the performance curve of force vs. velocity, and Figure 3b , which shows the performance curve of force v. relative position.
  • the test procedure measured the forces produced in the seat damper with a 2.54 cm (one inch) stroke at 5.08 and 20.32 cm/s (2 and 8 in/s) and 0, 1 and 2 amps.
  • a magnetorheological fluid was prepared by mixing 20% ATW-230 iron, 1% lithium hydroxy stearate, and the remaining volume (79%) of a synthetic hydrocarbon oil derived from poly- ⁇ -olefin sold under the name Durasyn® 162.
  • the fluid obtained was tested in a truck seat damper and the results illustrated in Figure 4a , which shows the performance curve of force vs. velocity, and Figure 4b graphically representing the performance curve of force v. relative position.
  • the test procedure measured the forces produced in the seat damper with a 2.54 cm (one inch) stroke at 5.08 and 20.32 cm/s (2 and 8 in/s) and 0, 1 and 2 amps. As shown in the Figures, force spikes (dots above solid lines) were evident when no friction reducing additive was present.
  • a magnetorheological fluid was prepared by mixing 20% ATW-230 iron, 1% lithium hydroxy stearate, 0.1% of a commercially available organomolybdenum compound and the remaining volume (77%) of a synthetic hydrocarbon oil derived from poly- ⁇ -olefin sold under the name Durasyn® 162.
  • the fluid obtained was tested in a truck seat damper and the results illustrated in Figure 5a , which shows the performance curve of force vs. velocity, and Figure 5b , which shows the performance curve of force v. relative position.
  • the test procedure measured the forces produced in the seat damper with a 2.54 cm (one inch) stroke at 5.08 and 20.32 cm/s (2 and 8 in/s) and 0, 1 and 2 amps.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Soft Magnetic Materials (AREA)
  • Lubricants (AREA)
  • Fluid-Damping Devices (AREA)

Claims (17)

  1. Composition magnétorhéologique comprenant :
    - des particules magnétosensibles caractérisées par une distribution de diamètres moyens en nombre (d50) de 6 à 100 micromètres, dans lesquelles plus de 50 % des particules ont une forme irrégulière, et
    - au moins un agent additif choisi à partir d'un composé de molybdène inorganique, un polymère fluorocarboné, ou leurs mélanges.
  2. Composition magnétorhéologique selon la revendication 1, dans laquelle les particules magnétosensibles ont une distribution de diamètres moyens en nombre de 10 à 60 micromètres.
  3. Composition magnétorhéologique selon la revendication 1, dans laquelle les particules magnétosensibles ont une répartition de diamètres moyens en nombre de 15 à 30 micromètres.
  4. Composition magnétorhéologique selon la revendication 1, dans laquelle l'additif est présent dans une quantité de 0,1 à 10 pourcent en poids des particules magnétosensibles.
  5. Composition magnétorhéologique selon l'une quelconque des revendications 1 à 4, dans laquelle les particules magnétosensibles et au moins un additif sont prévus en tant que poudre sensiblement sèche.
  6. Composition magnétorhéologique selon l'une quelconque des revendications 1 à 5, dans laquelle les particules magnétosensibles comprennent des particules de fer contenant au moins 95 % de fer obtenues par atomisation d'eau.
  7. Composition magnétorhéologique selon la revendication 1, dans laquelle les particules magnétosensibles sont prévues dans une quantité de 60 à 90 pourcent en poids de la composition magnétorhéologique totale.
  8. Composition magnétorhéologique selon la revendication 1, dans laquelle les particules magnétorhéologiques sont des particules de fer contenant moins de 1 % de carbone.
  9. Composition magnétorhéologique selon la revendication 1, dans laquelle l'additif est un sulfure de molybdène ou un phosphate de molybdène.
  10. Composition magnétorhéologique selon la revendication 9, dans laquelle l'additif est du disulfure de molybdène.
  11. Composition magnétorhéologique selon la revendication 1, dans laquelle l'additif est un polymère fluorocarboné.
  12. Composition magnétorhéologique selon la revendication 11, dans laquelle l'additif est du polytétrafluoroéthylène.
  13. Composition magnétorhéologique selon la revendication 1, comprenant des particules magnétosensibles non sphériques ayant une répartition de diamètres moyens en nombre de 10 à 60 micromètres et du disulfure de molybdène ou polytétrafluoroéthylène dans une quantité de 0,1 à 10 pourcent en poids des particules magnétosensibles.
  14. Fluide magnétorhéologique comprenant la composition magnétorhéologique selon l'une quelconque des revendications 1 à 13 et un fluide porteur.
  15. Fluide magnétorhéologique selon la revendication 14, dans lequel le fluide porteur est choisi dans le groupe consistant en les huiles grasses naturelles, de l'huile minérale, du polyphényléther, de l'ester d'acide dibasique, de l'ester de néopentylpolyol, de l'ester de phosphate, du polyester, de l'huile cycloparaffine, de l'huile paraffine, de l'huile hydrocarbonée insaturée, de l'huile hydrocarbonée synthétique, de l'huile naphténique, de l'ester de l'acide monobasique, du glycol ester, du glycol éther, de l'hydrocarbure synthétique, du polyéther perfluoré et de l'hydrocarbure halogéné.
  16. Dispositif magnétorhéologique comprenant la composition magnétorhéologique selon l'une quelconque des revendications 1 à 13.
  17. Dispositif magnétorhéologique selon la revendication 16, choisi dans le groupe consistant en freins, pistons, embrayages, amortisseurs, appareils de musculation, structures composites contrôlables et éléments structurels.
EP01932974A 2000-05-03 2001-05-03 Composition magnetorheologique Expired - Lifetime EP1279175B1 (fr)

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US564124 2000-05-03
US09/564,124 US6395193B1 (en) 2000-05-03 2000-05-03 Magnetorheological compositions
PCT/US2001/014358 WO2001084568A2 (fr) 2000-05-03 2001-05-03 Composition magnetorheologique

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EP1279175B1 true EP1279175B1 (fr) 2008-04-09

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107779247A (zh) * 2017-10-23 2018-03-09 青岛科技大学 一种二硫化钼/氧化钛纳米复合颗粒电流变液及其制备方法

Families Citing this family (47)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6818143B2 (en) * 2000-04-07 2004-11-16 Delphi Technologies, Inc. Durable magnetorheological fluid
US7217372B2 (en) * 2000-05-03 2007-05-15 Lord Corporation Magnetorheological composition
US6395193B1 (en) * 2000-05-03 2002-05-28 Lord Corporation Magnetorheological compositions
US6679999B2 (en) * 2001-03-13 2004-01-20 Delphi Technologies, Inc. MR fluids containing magnetic stainless steel
US20040119045A1 (en) * 2001-05-24 2004-06-24 Katsuhiko Hata Magnetoviscous fluid
US6881353B2 (en) * 2001-08-06 2005-04-19 General Motors Corporation Magnetorheological fluids with stearate and thiophosphate additives
US20030025100A1 (en) * 2001-08-06 2003-02-06 Ulicny John C. Magnetorheological fluids with stearate and thiophosphate additives
US6787058B2 (en) 2001-11-13 2004-09-07 Delphi Technologies, Inc. Low-cost MR fluids with powdered iron
US7736394B2 (en) 2002-08-22 2010-06-15 Victhom Human Bionics Inc. Actuated prosthesis for amputees
JP4808026B2 (ja) 2002-08-22 2011-11-02 ヴィクソム ヒューマン バイオニクス インコーポレーテッド 膝上部肢切断患者用の駆動源付き義足
US6751004B2 (en) 2002-10-31 2004-06-15 Hewlett-Packard Development Company, L.P. Optical system with magnetorheological fluid
US6820846B2 (en) 2003-04-07 2004-11-23 Raytheon Company Multiple ball joint gimbal
US7101487B2 (en) * 2003-05-02 2006-09-05 Ossur Engineering, Inc. Magnetorheological fluid compositions and prosthetic knees utilizing same
WO2005037966A1 (fr) * 2003-10-15 2005-04-28 Ashland Inc. Composition fluide absorbant les chocs contenant des nanostuctures
US20050107889A1 (en) 2003-11-18 2005-05-19 Stephane Bedard Instrumented prosthetic foot
US7815689B2 (en) 2003-11-18 2010-10-19 Victhom Human Bionics Inc. Instrumented prosthetic foot
US8057550B2 (en) 2004-02-12 2011-11-15 össur hf. Transfemoral prosthetic systems and methods for operating the same
US7637959B2 (en) 2004-02-12 2009-12-29 össur hf Systems and methods for adjusting the angle of a prosthetic ankle based on a measured surface angle
CA2559890C (fr) * 2004-03-10 2014-01-07 Ossur Hf Systeme de commande et procede pour un genou prothetique
US20050283257A1 (en) * 2004-03-10 2005-12-22 Bisbee Charles R Iii Control system and method for a prosthetic knee
US7070708B2 (en) 2004-04-30 2006-07-04 Delphi Technologies, Inc. Magnetorheological fluid resistant to settling in natural rubber devices
US20060136072A1 (en) * 2004-05-07 2006-06-22 Bisbee Charles R Iii Magnetorheologically actuated prosthetic knee
DE102004041651B4 (de) * 2004-08-27 2006-10-19 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Magnetorheologische Materialien mit magnetischen und nichtmagnetischen anorganischen Zusätzen und deren Verwendung
DE102004041649B4 (de) * 2004-08-27 2006-10-12 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Magnetorheologische Elastomere und deren Verwendung
DE102004041650B4 (de) * 2004-08-27 2006-10-19 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Magnetorheologische Materialien mit hohem Schaltfaktor und deren Verwendung
EP1848380B1 (fr) 2004-12-22 2015-04-15 Össur hf Systemes et procedes de traitement du mouvement de membre
US8801802B2 (en) 2005-02-16 2014-08-12 össur hf System and method for data communication with a mechatronic device
SE528516C2 (sv) 2005-04-19 2006-12-05 Lisa Gramnaes Kombinerat aktivt och passivt benprotessystem samt en metod för att utföra en rörelsecykel med ett sådant system
DE102005034925B4 (de) * 2005-07-26 2008-02-28 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Magnetorheologische Elastomerkomposite sowie deren Verwendung
WO2007027808A2 (fr) 2005-09-01 2007-03-08 össur hf Systeme et methode pour determiner des transitions de terrain
JP4808506B2 (ja) * 2006-02-14 2011-11-02 スミダコーポレーション株式会社 複合磁性シート、コイル用複合磁性シートおよびそれらの製造方法
US7822522B2 (en) * 2006-05-31 2010-10-26 Techno-Sciences, Inc. (corporation) Adaptive energy absorption system for a vehicle seat
US7921973B2 (en) * 2006-05-31 2011-04-12 Techno-Sciences, Inc. Adaptive energy absorption system for a vehicle seat
US7878312B2 (en) * 2006-05-31 2011-02-01 University Of Maryland Adaptive energy absorption system for a vehicle seat
JP5222296B2 (ja) * 2006-09-22 2013-06-26 ビーエーエスエフ ソシエタス・ヨーロピア 磁性流体組成物
DE102007017589B3 (de) * 2007-04-13 2008-10-02 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Dämpfungsvorrichtung mit feldsteuerbarer Flüssigkeit
CA2698685A1 (fr) * 2007-09-07 2009-03-12 The University Of Akron Polymeres magnetiques moleculaires
US20090302516A1 (en) * 2008-06-05 2009-12-10 Lockheed Martin Corporation System, method and apparatus for control surface with dynamic compensation
US8361341B2 (en) * 2009-03-09 2013-01-29 GM Global Technology Operations LLC Magnetorheological compositions including nonmagnetic material
EP2621414B1 (fr) 2010-09-29 2019-03-13 Össur HF Dispositifs prosthétiques et orthétiques et procédés et systèmes pour commander ceux-ci
JP5587734B2 (ja) * 2010-10-27 2014-09-10 協同油脂株式会社 磁気粘性流体組成物
US9060884B2 (en) 2011-05-03 2015-06-23 Victhom Human Bionics Inc. Impedance simulating motion controller for orthotic and prosthetic applications
WO2014133975A1 (fr) 2013-02-26 2014-09-04 össur hf Pied prothétique à stabilité et retour d'énergie élastique améliorés
WO2017151562A1 (fr) 2016-02-29 2017-09-08 Lord Corporation Additif pour fluides magnétorhéologiques
CN106710774A (zh) * 2016-12-23 2017-05-24 上海工程技术大学 一种高稳定性磁流变液及其制备方法
CN110938272B (zh) * 2019-12-19 2020-10-23 中国科学院长春应用化学研究所 一种复合阻尼材料及其制备方法
US11879519B2 (en) 2022-04-22 2024-01-23 Yamashita Rubber Co., Ltd. Magnetorheological fluid

Family Cites Families (30)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL171985B (nl) 1951-08-23 Rhone-Poulenc Industries Te Parijs. Werkwijze voor het bereiden van preparaten met werking tegen schistosomiasis, de aldus verkregen gevormde preparaten en werkwijze voor het bereiden van 1,2-dithioolverbindingen.
US2772761A (en) * 1951-12-17 1956-12-04 Lear Inc Electromagnetic clutch with particulate clutching medium
US2804955A (en) * 1953-03-05 1957-09-03 Eaton Mfg Co Magnetic fluid mixture coupling
FR1371965A (fr) * 1963-04-03 1964-09-11 Bull Sa Machines Perfectionnements aux joints magnétiques frottants
US3666670A (en) * 1969-08-01 1972-05-30 Vulcan Materials Co Pulverulent drain cleaning composition
US4356098A (en) 1979-11-08 1982-10-26 Ferrofluidics Corporation Stable ferrofluid compositions and method of making same
JPH0633391B2 (ja) * 1985-05-07 1994-05-02 日本メクトロン株式会社 パ−フロロエ−テル系組成物およびその製造方法
US4849120A (en) 1986-05-13 1989-07-18 Price John T Magnetically controllable couplings containing ferrafluids
JPH0682577B2 (ja) * 1989-01-18 1994-10-19 新日本製鐵株式会社 Ｆｅ―Ｓｉ系合金圧粉磁心およびその製造方法
US6503414B1 (en) * 1992-04-14 2003-01-07 Byelocorp Scientific, Inc. Magnetorheological polishing devices and methods
US5449313A (en) 1992-04-14 1995-09-12 Byelocorp Scientific, Inc. Magnetorheological polishing devices and methods
US5284330A (en) 1992-06-18 1994-02-08 Lord Corporation Magnetorheological fluid devices
US5277281A (en) 1992-06-18 1994-01-11 Lord Corporation Magnetorheological fluid dampers
US5354488A (en) * 1992-10-07 1994-10-11 Trw Inc. Fluid responsive to a magnetic field
CA2148000C (fr) 1992-10-30 2000-10-10 Keith D. Weiss Matieres magnetorheologiques thixotropes
US5363821A (en) * 1993-07-06 1994-11-15 Ford Motor Company Thermoset polymer/solid lubricant coating system
US5518639A (en) 1994-08-12 1996-05-21 Hoeganaes Corp. Powder metallurgy lubricant composition and methods for using same
US5816372A (en) * 1994-09-09 1998-10-06 Lord Corporation Magnetorheological fluid devices and process of controlling force in exercise equipment utilizing same
US5641920A (en) * 1995-09-07 1997-06-24 Thermat Precision Technology, Inc. Powder and binder systems for use in powder molding
US5900184A (en) * 1995-10-18 1999-05-04 Lord Corporation Method and magnetorheological fluid formulations for increasing the output of a magnetorheological fluid device
US5670077A (en) 1995-10-18 1997-09-23 Lord Corporation Aqueous magnetorheological materials
US5683615A (en) 1996-06-13 1997-11-04 Lord Corporation Magnetorheological fluid
US5705085A (en) 1996-06-13 1998-01-06 Lord Corporation Organomolybdenum-containing magnetorheological fluid
US5984056A (en) 1997-04-24 1999-11-16 Bell Helicopter Textron Inc. Magnetic particle damper apparatus
US5846447A (en) * 1997-08-26 1998-12-08 E. I. Du Pont De Nemours And Company Process for forming a dispersion of polytetrafluoroethylene
US5985168A (en) 1997-09-29 1999-11-16 University Of Pittsburgh Of The Commonwealth System Of Higher Education Magnetorheological fluid
US6547983B2 (en) * 1999-12-14 2003-04-15 Delphi Technologies, Inc. Durable magnetorheological fluid compositions
US6818143B2 (en) * 2000-04-07 2004-11-16 Delphi Technologies, Inc. Durable magnetorheological fluid
US6395193B1 (en) * 2000-05-03 2002-05-28 Lord Corporation Magnetorheological compositions
US7217372B2 (en) * 2000-05-03 2007-05-15 Lord Corporation Magnetorheological composition

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107779247A (zh) * 2017-10-23 2018-03-09 青岛科技大学 一种二硫化钼/氧化钛纳米复合颗粒电流变液及其制备方法

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US7070707B2 (en) 2006-07-04
DE60133540T2 (de) 2009-06-18
WO2001084568A3 (fr) 2002-03-21
JP2003533016A (ja) 2003-11-05
DE60133540D1 (de) 2008-05-21
US6395193B1 (en) 2002-05-28
EP1279175A2 (fr) 2003-01-29
WO2001084568A2 (fr) 2001-11-08
US20040140447A1 (en) 2004-07-22

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